Apparatus for coating containers



Feb. 13, 1962 J. PODLIPNIK 3,020,879

v APPARATUS FOR COATING CONTAINERS Filed March 13, 1959 2 Sheets-Sheet 2 E I INVENTOR. JOHN PODL/PN/A ATTORNEYS United States Patent 3,020,879 APPARATUS FOR COATING CONTAINERS John Podlipnik, Palos Heights, Ill., assignor to Sinclair lB ielining Company, New York, N.Y., a corporation of awe Filed Mar. 13, 1959, Ser. No. 799,244 11 Claims. (Cl. 118-423) This invention relates to an apparatus for continuously coating articles of fibrous materials With a wax composition and the like. More specifically, this invention relates to a means for improving carton quality by improving surface wax coverage while maintaining a preformed shape.

During the manufacture of wax-covered fibrous, e.g. paper-board, containers such as milk cartons, a machine performs these functions: a fiat, pre-cut carton is opened, squared and glued at the bottom with a thermosetting adhesive. The carton is then placed in a metal basket and the carton plus the basket is passed through a liquid, predominantly parafiin wax bath. The carton remains in the basket during draining, after which it is transported to a cooler. Then, an automatic filler meters a correct quantity of milk into the carton after which the top is folded and stapled. The finished carton is thendelivered to the conveyor for casing.

A major problem currently experienced in the production of this type of paperboard cartons concerns the presence of unwaxed areas on the outside of the cartons. These areas are commercially termed dry spots and their presence tends to cause bulging of the carton when the exterior is exposed to moisture such as occurs when the carton is iced during truck delivery and sweats during storage. 7 I

Various techniques have been employed to improve the exterior surface wax coverage, such as placing expensive additives, e.g. polyethylene, in the wax, or coating at relatively low temperatures or high-wax levels; however, these operations have certain disadvantages such as excessive wax consumption, cost, or wax build-up on machine parts. An object of this invention is to provide a smooth uniform Wax coating surface on the paperboard containers without the presence of air bubbles or the rippled serpentine characteristics often found in such wax coatings. Further, the apparatus of my invention specifically eliminates the vertical dry spots on the outside of the top and bottom drain panels of the carton without requiring the use of polyethylene in the predominantly parafiinwax coating composition or unusual coating conditions. These and other objects are accomplished by the apparatus which comprises my present invention as shown in the following description illustrated in the accompanying drawings and distinctly pointed out and set forth in the appended claims which form part of the disclosure herewith.

Generally, my invention involves the known apparatus for the manufacture of wax-coated containers from fiat pre-cut cartons by opening, squaring and gluing with a thermosetting adhesive, placing the carton in a metal basket and immersing the carton-containing basket in a liquid wax bath, removing the carton from the bath, draining the carton and subsequently cooling. Specifically, this invention includes an improved work-holder or basket for transporting the object to be coated through the immersion bath and into the draining area. The basket of this invention, when compared with known 3,020,879 Patented Feb. 13,:1 962 FIGURE 1 presents a diagrammatic or flow sheet type of drawing illustrating my apparatus;

FIGURE 2 presents a vertical section of one form of the coating apparatus which includes an immersion tank, dipping means and a wax fluid taken on line 22 of FIGURE 1;

FIGURE 3 shows a small portion of the conveying means where articles to be coated are placed in the immersion baskets and coated objects are removed from the baskets;

FIGURE 4 shows the positioning of the containers on the conveyor during the immersion stage; and

FIGURE 5 shows the details of my new basket construction.

Referring to the drawings, FIGURE 1 illustrates diagrammatically an apparatus for the production of paperboard milk containers such as the well-known Pure Pak containers. A fiat pre-cut carton 1 is opened, squared and glued with a thermosetting adhesive in forming area 2. The carton is conveyed by a work moving means such as a conveyor mechanism 3 to a work holding means I such as a basket 4. The basket is attached to a constructures, has a decreased contact area between the sides of the basket and the fibrous container therein. This new longitudinally braced holder has side panels characterized by the minimum metal area required to maintain strength and durability. My invention will be described with reference to the drawings in which:

veyor mechanism 5 for introducing the articles into and withdrawing them from an enclosed wax bath 6 usually maintained at a temperature of about to 190 F., preferably about to F. After withdrawing the carton 1 and basket 4 from the wax bath 6, the carton is ejected or dropped onto a hot plate 7 Where means such as a guide or conveying chains (not shown) move the coated carton to a cooling area 8 where the base of the carton is initially dipped in a water bath 9.. The cooling is aided by air blower 10 which generally maintains a temperature of about 40 to 60 F., e.g. about 50 F., in the cooling area. A moving means such as a conveyor mechanism 11 moves the. cooled carton to a filling and casing area 12 where milk or other liquids are injected into the hollow carton. The filled carton is then cased and readied for delivery or storage.

FIGURE 2 generally shows an immersion tank containing fluid and the parts of the coating apparatus of thte present invention. An enclosed tank casing 13 holds the liquid wax coating bath -6 and also a mechanism for introducing the baskets 4 into and withdrawing them from the bath. The level of the upper surface of the bath is shown as 15A and the conveyor for handling the .cartons as 5. The baskets are attached to the conveying mechanism 5 which passes around sprockets 15 and 16, respectively, in the lower and upper portions of tank 13, for moving the conveyor and the baskets through the wax bath.

During the initial immersion period the baskets move downwardly into the parafiin wax until filling and immersion of the carton occurs. The center panels 18 of the baskets 4 are mounted on conveyor 5 at an angle slightly above horizontal so that one end of the basket and its contained carton is lower than the other. The lower end of the carton during the initial immersion is the closed bottom end. As the baskets reach the lower pulley 15 and begin the upward pass, they become reversed or so angled, i.e. about 180 from that at initial immersion, that draining takes place at the opened filling or top end of the carton which is now at a position lower than the closed bottom end of the carton. As the baskets leave the immersion bath in this position the cantons begin the outside and inside drain cycle. which continues until the conveyor 5 reaches the upper pulley 16. As the basket rides over pulley '16 it becomes positioned as during initial immersion so that only the outside of the basket can drain, thus beginning the outside drain cycle. The

' angle of mounting of the baskets on theconiveyor is such that the container will remain in the basket during immersion and draining against the forces of gravity and until actually ejected out of the basket by mechanical means or further tilting of the basket. Alternatively, mechanical means can be provided for holding the container in the basket during the draining periods and before immersion. The conveyor mechanism is of course activated by a power means such as electric motors or the like (not shown). If desired, a heating coil (not shown) can be placed in the immersion tank so as to maintain the wax composition at the desired temperature during coating.

FIGURE 4 shows the positioning of the carton during the coating operation. As the conveyor mechanism 5 moves the carton through the immersion bath on the downward pass, the cartons are angled vertically with the open end extending upwardly. As the cartons begin their upward pass the open ends of the cartons are extended downwardly. Thus, it is readily apparent that sufiicient interior and exterior coating and later draining take place in the operations of this invention.

After the outside drain cycle the basket reaches the unloading and loading station 17. A possible construction of the station is shown in FIGURE 3 where the coating carton is ejected or dropped onto a hot plate 7 for further draining and is moved by means such as guides, claws, conveyors and the like to the cooling area. The coated carton is ejected from the basket 4 by a mechanical pusher inserted into the basket and the conveyor mechanism 5 moves a mechanically inserted uncoated carton 1A and the basket holding it into the wax bath. An example of the apparatus used in this loading-unloading procedure is shown in US. Patent No. 2,364,868. The coated carton 1 then reaches the cooling area 8 as shown in FIGURE 1 where the base of the carton is passed through a water bath 9. The carton is removed from the bath and subsequently cooled by cool air from blower 10. Representative apparatus of the type utilized for cooling in this invention are shown in US. Patent No. 2,415,677 and US. Patent No. 2,381,360.

Referring now more specifically to FIGURE 5, the open ended basket or work-holder 4 has a center panel 18. Longitudinal ribs 22 are attached to and extend along the length of the center panel 18 near the sides of the panel. Ribbed side panels 19 and 20 are attached at an angle substantially perpendicular to panel 18. The side panels are formed by a frame or peripheral border 30 and cross-members or screens 23 shown as expanded metal. Ribs 24 and 25 are attached to and extend longitudinally at the respective sides of the side panels 19, while ribs 26 and 27 are similarly attached to panel 20. These ribs are on the inside or facing sides of their respective panels. If desired, guards 28 and 2? may be attached to and project inwardly from the respective side panels. The guards are substantially perpendicular to the side panels and thus generally parallel to center panel 18 to aid in holding the cartons within the basket as they travel around the conveyor path.

FIGURE 5 shows the preferred design of this basket but other holders having side panels 19 and 20 whose surfaces are less than 60% solid, e.g. metal, in the area adjacent or opposite a contained carton may be satisfactorily employed, provided that the openings are distributed throughout the portion of the side panels adjacent the container and so long as the requirements of strength and durability are maintained. In addition, for each side panel the area of contact, i.e. the ribs, with the fibrous material conveyed should not exceed about of the adjacent carton side, with a preferred amount being about 5% or less. Further, the ribs of the center and side panels should be in a longitudinal position with respect to the carton the basket holds; or stated in another way the ribs extend towards the open ends of the basket or in the direction of carton ejection from the basket to minimize wiping during container removal. The basket of this invention may be constructed of stainless steel, aluminum,

galvanized iron, or other non-rusting metals or other materials which provide the desired strength and rigidity. A preferred metal would be of 16 gauge or heavier. Normally, the carton coated lies on one of the side panels 19 or 20 during immersion and draining.

The following test was conducted using standard Pure Pak half-gallon cartons coated with a commercial petroleum wax, predominantly paraflin wax composition containing no polyethylene. This test consisted of immersing a carton in a basket for a period of 9 seconds at about F. followed by an outside and an inside drain beginning as the basket leaves the wax in the immersion tank in the upward pass, of 12.6 seconds with a subsequent outside drain beginning as the basket reaches pulley 16 and continues until the carton reaches the cooling area, of 13.2 seconds and then cooling for 23 seconds. The purpose of this test was to show the improved coating characteristics of the new baskets of this invention, as compared with current commercial dip-tank baskets having latitudinal ribs for carton resting and side panels which are substantially more than 60% solid metal.

TABLE 1 Percent uncovered area on exterior of resting panels Current New Pure-Pak Basket Dip-Tank Basket 0 15 5 40 0 10 Carton D- 0 l5 These data show that the new basket results in greatly improved exterior coverage of the object coated which in turn reduces bulging and improves carton durability. By the term resting panels is meant the panels of each carton on which the carton rests against the basket side panels during the immersion and draining periods.

I claim:

1. In a coating apparatus for coating a container with wax compositions comprising an immersion tank for containing liquid wax, an open ended basket having side panels for holding said container, means for moving the basket into and out of said wax with the container resting on at least one of said side panels, the improvement comprising said basket having a center panel, side panels attached at a substantially perpendicular angle at each side of the center panel, ribs attached to said side panels and extending toward said open end for holding said container out of contact with the side panels, said side panels having a maximum area of contact with the container of about 10%, and each side panel having a solid surface area of less than about 60% of the total surface area of the side panel.

2. The apparatus of claim 1 wherein said center panel has ribs extending towards said open end for holding said container out of contact with the center panel.

3. The apparatus of claim 2 wherein a guard is attached to and projects inwardly from each of the side panels at a substantially perpendicular angle.

4. The apparatus of claim 1 having in addition means for contacting the immersed and withdrawn container with cooling air.

5. In a coating apparatus for coating a paperboard container with wax compositions comprising a closed immersion tank for containing liquid wax, a conveyor, an open ended basket on said conveyor for holding said container, said conveyor being adapted to move said basket into and out of said wax, the improvement comprising said basket having a center panel, side panels attached at a substantially perpendicular angle at each side of the center panel, ribs attached to said side panels and extending toward said open end for holding said container out of contact with the side panels, said side panels having a maximum area of contact with the container of about and each side panel having a solid surface area of less than about 60% of the total surface area of the side panel, the center panel of said basket being attached to said conveyor at an angle to the horizontal such that the container will remain in the basket while being conveyed into and out of said wax, said conveyor being closed around an upper support means located in the upper portion of said tank and around a lower support means located in the lower portion of said tank, the passing of said conveyor around the support means serving to reverse said basket and said upper support means being sufficiently above said wax to provide for draining of the container as the basket moves away from said wax and over the upper support.

6. The apparatus of claim 5 wherein said center panel has ribs extending towards said open end for holding said container out of contact with the center panel.

7. The apparatus of claim 6 wherein a guard is attached to and projects inwardly from each of the side panels at a substantially perpendicular angle.

8. The apparatus of claim 5 having in addition means for contacting the immersed and withdrawn container with cooling air.

9. An open ended basket for holding a container comprising a center panel, side panels attached at a substantially perpendicular angle at each side of the center panel, ribs attached to said side panels and extending toward said open end for holding said container out of contact with the side panels, said side panels having a maximum area of contact with the container of about 10%, and each side panel having a solid surface area of less than about of the total surface area of the side panel.

10. The basket of claim 9 wherein said center panel has ribs extending towards said open end for holding said container out of contact with the center panel.

11. The basket of claim 10 wherein a guard is attached to and projects inwardly from each of the side panels at a substantially perpendicular angle.

References Cited in the file of this patent UNITED STATES PATENTS 1,151,636 Weiss etal. Aug. 31, 1915 1,321,925 Lake Nov. 18, 1919 1,364,648 Shirlow Jan. 4, 1921 1,461,760 Morinsky July 17, 1923 2,289,763 Earp July 14, 1942 2,651,284 Zinn et a1. Sept. 8, 1953 2,699,750 Wittkuhns et a1. Jan. 18, 1955 

